Races
Fun Trails Chichibu & Okumusashi
Japan, November. 100 mi on 75% trail. +1,980 ft of climbing. 32 hours cutoff.
- Start66 ft
- High121 ft
- Low57 ft
- Finish69 ft
Geometryderived
Weather at the cruxderived
At hour 8 of race, feels like 20 C (66 F).Sample of 7 race days, medium confidence.At hour 8 of race, apparent temperature P90 is 20 C / 68 F.
The cruxHumid climbs, ridge exposure, and aid gaps in remote terrain (near mile 65)
Course DNA
The Course
Fun Trails Chichibu & Okumusashi runs 100 mi through Japan. +1,980 ft gain and -1,977 ft loss. Surfaces skew 75% trail / 20% dirt road / 5% paved. Humid climbs, ridge exposure, and aid gaps in remote terrain. High point near 121 ft. Low near 57 ft. November temps run 50°F to 85°F. The course rewards patience early and punishes rushed descents after mile 50.
The Work
Train for 1,980 feet of climbing across 100 mi. Back-to-back long runs on trail. Practice power-hiking grades above 15 percent. 32 hours total means limited margin: rehearse fueling every 45 to 60 minutes and downhill eccentric work weekly. Technicality 5/10. Build a block that simulates the crux near mile 65.
Kit
November in Japan: plan for 50°F to 85°F. Mandatory shell if rain is in forecast. Headlamp with spare batteries if 32 hours pushes past dark. Poles help on sustained climbs above mile 25. Vest capacity for 2 liters minimum. Shoes matched to 75% trail: lugs for mud, rock plate if the course turns technical after mile 50.
Race Day
Hold effort through mile 25. The field often splits on the first big climb after mile 50. Humid climbs, ridge exposure, and aid gaps in remote terrain near mile 65 is where time is won or lost. Walk the steep pinches. Run the flats and gentle downhills. Crew at major aids: socks, calories, ice if hot. Transitions under 5 minutes when possible. Final third is 33 miles of fatigue management. Finish with reserve for the last descent.
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